What and when to eat? Investigating the feeding habits of an intertidal herbivorous starfish

Martinez, Aline S.; Byrne, Maria; Coleman, Ross A.

doi:10.1007/s00227-016-2942-7

Cited by 12 publications

(8 citation statements)

References 90 publications

(97 reference statements)

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“…This particular habitat was sampled more extensively in the video-recorded 150 m 2 plots which revealed higher densities of P. cumingi and N. armata than the wall transects, underscoring the important in uence of habitat variation on sea star abundance. Our observed densities were also low in comparison to other observations of sea star densities in sandy and rocky intertidal areas worldwide, indicating subtidal rock walls may be less densely populated than atter areas in general (Scheibling and Metaxas 2008;Martinez et al 2016).…”

Section: Abundance and Distributioncontrasting

confidence: 87%

Stargrazing: Trophic ecology of sea stars in the Galápagos rocky subtidal zone

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Lamb

et al. 2021

Preprint

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Sea stars (class Asteroidea) can play powerful and wide-ranging roles as consumers of algae and prey items in benthic ecosystems worldwide. In the Galápagos rocky subtidal zone, sea stars are abundant and diverse but their distribution, feeding habits and ecological impacts have received little attention. We compared diets and distributions across the six most abundant sea star species to examine functional roles of this important group. Bi-annual censuses carried out between 2006–2014 at two depths (6-8m, 12-15m) at 12 sites in Galápagos identified two abundance “hotspots” and revealed higher densities at locations with more heterogeneous benthic topographies. Field surveys revealed a high incidence of feeding (35–68% of individuals across species) and distinct diets were evident for each species in terms of food items and dietary breadth, suggesting niche partitioning. Most species can be classified as facultative herbivores, with diets dominated by crustose and turf algae supplemented by a small proportion of sessile invertebrates. The two most abundant species (Pentaceraster cumingi and Nidorellia armata) had the narrowest diets. Field prey selectivity experiments identified P. cumingi as a size-selective predator of the pencil urchin Eucidaris galapagensis. In field caging experiments, N. armata reduced biomass of unbleached crustose coralline algae and macroalgae by 72% and 52%, respectively. In the context of emerging threats such as disease, ocean acidification and climate change, a deeper understanding of distinct functional roles can inform ecological models and management plans.

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Section: Abundance and Distributioncontrasting

confidence: 87%

Stargrazing: Trophic ecology of sea stars in the Galápagos rocky subtidal zone

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Low

Lamb

et al. 2021

Preprint

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“…At Knysna it is abundant only in the lagoonal reach and in some lagoon-like backwater areas of the marine embayment (see below), but there it occurs both subtidally and intertidally in densities of [ 1000 m -2 . Parvulastra grazes microalgal-rich biofilms (Jackson et al 2009;Martinez et al 2016) and this dependence on a high-light regime may account for its relative intertidal abundance.…”

Section: Discussionmentioning

confidence: 99%

Do beds of subtidal estuarine seagrass constitute a refuge for macrobenthic biodiversity threatened intertidally?

Barnes

Claassens

2020

Biodivers Conserv

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Biodiversity differentials between macrobenthic assemblages associated with adjacent intertidal and subtidal areas of a single seagrass system were investigated for the first time. Assemblage metrics of conservation relevance—faunal abundance and its patchiness, faunal richness, and beta diversity—were examined at four contrasting dwarf-eelgrass localities in the Knysna estuarine bay, part of South Africa's Garden Route National Park but a system whose intertidal areas are heavily impacted anthropogenically. Faunal assemblages were significantly different across all localities and between subtidal and intertidal levels at each locality although their taxonomic distinctness was effectively constant. Although, as would be expected, there were clear trends for increases in overall numbers of species towards the mouth at all levels, few generalities relating to the relative importance of the subtidal seagrass habitat were evident across the whole system—magnitude and direction of differentials were contingent on locality. Shore-height related differences in assemblage metrics were minor in the estuarine and lagoonal zones but major in the marine compartment, although the much greater subtidal faunal abundance there was largely consequent on the superabundance of a single species (the microgastropod Alaba pinnae), intertidal zones then displaying the greater species diversity due to greater equitability of species densities. Along its axial channel, the Knysna subtidal seagrass does not support richer versions of the intertidal polychaete-dominated assemblages fringing it; instead, it supports different and more patchily dispersed gastropod-dominated ones. At Knysna at least, the subtidal hardly constitutes a reservoir of the seagrass biodiversity present intertidally.

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“…across locations), but this result was positively associated with the cover of bare rock within the previously occupied pool. Since this species uses the pool as foraging grounds during low tide (Martinez, Byrne & Coleman ), movements among rock pools may decrease when more food resource is available in the resident pool. Whether the abundance of conspecifics and other competing grazers could influence this result requires future investigations.…”

Section: Discussionmentioning

confidence: 99%

“…We further investigated the potential effect of habitat quality on detected site fidelity. The extent of rock covered by epilithic microalgae, hereafter called bare rock, was used as proxy for habitat quality since P. exigua predominantly forages on this substratum (Martinez, Byrne & Coleman ). A logistic regression (Sokal & Rohlf ) was done to test the effect of relative bare rock cover on rock pool fidelity of starfish.…”

Section: Methodsmentioning

confidence: 99%

Incorporating in situ habitat patchiness in site selection models reveals that site fidelity is not always a consequence of animal choice

Martinez

Queiroz

Bryson

et al. 2017

Journal of Animal Ecology

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Understanding site fidelity is important in animal ecology, but evidence is lacking that this behaviour is due to an animal choosing a specific location. To discern site selection behaviour, it is necessary to consider the spatial distribution of habitats that animals can occupy within a landscape. Tracking animals and defining clear habitat boundaries, however, is often difficult. We use in situ habitat distribution data and animal movement simulations to investigate behavioural choice in site fidelity patterns. We resolved the difficulty of gathering data by working with intertidal rock pool systems, which are of manageable size and where boundaries are easy to define. Movements of the intertidal starfish Parvulastra exigua were quantified to test the hypotheses that (1) this species displays fidelity to a particular rock pool and that (2) rock pool fidelity is due to site selection behaviour. Observed patterns of individuals (n = 10 starfish) returning to a previously occupied rock pool (n = 5 pools per location) were tested against an expected null distribution generated through simulations of random movements within their natural patchy environment. Starfish exhibited site selection behaviour at only one location even though site fidelity was high (av. 7·4 starfish out of 10 found in test pools) in two of the three locations. The random chance of a starfish returning to a pool increased 67% for each metre further a rock pool was from the original pool, and 120% for each square metre increase in surface area of an original pool. The decision of returning to an original rock pool was influenced by food availability. When microalgal cover was >60%, there was a c. 50% chance of animals staying faithful to that pool. Our results show the importance to consider spatial distribution of habitats in understanding patterns of animal movement associated with animal choices and site fidelity. Returning to a particular place does not necessarily mean that an animal is homing; it may be the only place to go.

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What and when to eat? Investigating the feeding habits of an intertidal herbivorous starfish

Cited by 12 publications

References 90 publications

Stargrazing: Trophic ecology of sea stars in the Galápagos rocky subtidal zone

Stargrazing: Trophic ecology of sea stars in the Galápagos rocky subtidal zone

Do beds of subtidal estuarine seagrass constitute a refuge for macrobenthic biodiversity threatened intertidally?

Incorporating in situ habitat patchiness in site selection models reveals that site fidelity is not always a consequence of animal choice

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